Answer:
Coefficient in front of the 
in the balanced equation - 1
Explanation:
The unbalanced Chemical equation is shown below as:-
On the left hand side,
There are 1 boron atom and 3 fluorine atoms and 1 sodium and hydrogen atoms.
On the right hand side,
There are 2 boron atoms and 6 hydrogen atoms and 1 sodium and fluorine atoms.
Thus,
leftside, 
must be multiplied by 2 to balance boron and right side, 
must be multiplied by 6 to balance fluorine. Left side, 
must be multiplied by 6 to balance sodium and hydrogen atoms.
Thus, the balanced reaction is:-
<u>Coefficient in front of the in the balanced equation - 1</u>
A) C2H6O1
To find the emperical formula, divide each mole value by the smallest
For carbon, 0.013/0.0065 = 2
For hydrogen, 0.038/0.0065= 6
For oxygen, 0.0065/0.0065= 1
Emperical formula = C2H6O1
The first question's answer is
33.6 moles are needed to completely react with 84.0 moles of O2
